Various modes may be used for human-robot interaction (HRI). One mode of HRI is the use of a computer user interface. An example of this mode is the use of a computer to upload commands or instructions to the robot. Such interactions are generally reserved for a user that is familiar with computer programming and has in-depth knowledge of a robot's operation. Another mode of operation is using speech synthesis and speech recognition. For general public lacking technical knowledge of robots, a natural way of interacting with the robots is by speaking to the robots and listening to any speech generated by the robots. Such mode of operations is intuitive on the part of humans but may require hardware devices and computer programs to process and synthesize speeches.
One way of enhancing interactions between humans and robots is to use gestures. A gesture is a form of non-verbal communication made by bodily actions. By itself or in conjunction with speech, gestures allow individuals to communicate with others effectively.
Gestures can be categorized into different types. One category of gestures is emblems. Emblems refer to self-contained gestures whose meaning can be understood without spoken words. Emblems include, for example, waving a hand to say goodbye or hello. Iconics are a category of gestures used in conjunction with words to indicate concrete things. Iconics include, for example, tracing out a trajectory of a path. Metaphorics are a group of gestures that provide imagery of the abstract. Metaphorics include a gesture referring to the sides of an argument by appearing to be holding invisible items in left and right hands. Deictics are gestures that utilize parts of the body to point out both concrete and abstract things during a conversation. Deictics include, for example, using an arm with the index finger extended at a target of interest. Beats are a group of gestures that are expressed in rhythmic hand motions in synchrony with the cadences of speech. More than one type of gestures may be expressed during a course of speech.
Humanoid robots have appearance and features similar to humans. Hence, many people feel a natural affinity for these robots. However, the humanoid robots often remain stationary during interactions with humans. Hence, users often feel interactions with the robots unnatural and awkward compared to human.